div{
    width: 500px;
    height: 500px;
    background-color: aqua;
    > div3{
        width: 200px;
        height: 200px;
        background-color: blue;

    }

    div1{
        width: 400px;
        height: 400px;
        background-color: aquamarine;

        div2{
            width: 300px;
            height: 300px;
            background-color: bisque;
        }
    }
}


.box{
    width: 300px;
    height: 300px;
    background-color: blueviolet;
    &::before{
        content: '';
        display: block;
    }

    .box3{
        width: 200px;
        height: 200px;

        &:hover{
            color: red;
        }
    }
}